The entire disclosure of Japanese Patent Application No. 2007-89867, filed Mar. 29, 2007 is expressly incorporated by reference herein.
1. Technical Field
The present invention relates to liquid ejecting heads ejecting liquid and methods for manufacturing the same, and particularly to a method for manufacturing an ink jet recording head that ejects ink droplets through a nozzle aperture communicating with a pressure generating chamber by compressing the ink fed into the pressure generating chamber with a piezoelectric element.
2. Related Art
A type of ink jet recording head ejects ink droplets through a nozzle aperture communicating with a pressure generating chamber part of which is defined by a vibration plate. The ink in the pressure generating chamber is compressed to be ejected by deforming the vibration plate by use of a piezoelectric element. This type of ink jet recording head in practical use may include a longitudinal vibration mode piezoelectric actuator whose piezoelectric element expands and contracts in the axial direction of the element, or a flexural vibration mode piezoelectric actuator. In a known ink jet recording head using a flexural vibration mode piezoelectric actuator, for example, piezoelectric elements are provided for respective pressure generating chambers by cutting a piezoelectric material layer evenly deposited over the entire surface of a vibration plate into portions corresponding to the pressure generating chambers by lithography (Japanese Unexamined Patent Application Publication No. 2005-150491). According to Japanese Unexamined Patent Application Publication No. 2005-150491, the piezoelectric material layer preferably has a crystal structure oriented in the (100) plane or a rhombohedral crystal structure from the viewpoint of producing superior piezoelectric properties.
In such a type of ink jet recording head, unfortunately, repetitive driving of the piezoelectric element may vary the displacement of the piezoelectric element and result in unstable ejection. For example, the amount of ink ejected and the ink ejection speed become unstable. In particular, the displacement of the piezoelectric element is often reduced significantly in an early stage. The reduction of the displacement of the piezoelectric element degrades the printing quality. The same problem can occur in liquid ejecting heads ejecting liquid other than ink as well as ink jet recording heads.